<?php
$prize_arr = array( 
    '0' => array('id'=>1,'prize'=>'平板电脑','v'=>3), 
    '1' => array('id'=>2,'prize'=>'数码相机','v'=>5), 
    '2' => array('id'=>3,'prize'=>'音箱设备','v'=>10), 
    '3' => array('id'=>4,'prize'=>'4G优盘','v'=>12), 
    '4' => array('id'=>5,'prize'=>'Q币10元','v'=>20), 
    '5' => array('id'=>6,'prize'=>'下次没准就能中哦','v'=>50), 
); 
 
foreach ($prize_arr as $key => $val) { 
    $arr[$val['id']] = $val['v']; 
} 
 
$rid = getRand($arr); //根据概率获取奖项id 
$res['msg'] = ($rid==6)?0:1; //如果为0则没中 
$res['prize'] = $prize_arr[$rid-1]['prize']; //中奖项 
echo json_encode($res); 
 
//计算概率 
function getRand($proArr) { 
    $result = ''; 
 
    //概率数组的总概率精度 
    $proSum = array_sum($proArr); 
 
    //概率数组循环 
    foreach ($proArr as $key => $proCur) { 
        $randNum = mt_rand(1, $proSum); 
        if ($randNum <= $proCur) { 
            $result = $key; 
            break; 
        } else { 
            $proSum -= $proCur; 
        } 
    } 
    unset ($proArr); 
 
    return $result; 
}?>